Are you asking to close the frontend port when no backends are available?
–> Thats not supported. Please use intelligent l7 health checks, not simple layer 4 port checks from additional frontend proxy layers.

Are you asking to use external health checks for the backends?
–> Check external-check documentation.

I just want the emission/exposion of the currently well-known backend status.

Are you asking to close the frontend port when no backends are available?
–>
Thats not supported. Please use intelligent l7 health checks, not
simple layer 4 port checks from additional frontend proxy layers.

Do you mean using layer 7 checks (http request/response checks) from outside or from haproxy config?

Are you asking to use external health checks for the backends?
–> Check external-check documentation.

It says I would need to define a script on the server itself. This is something which I definitely need only if I would need to write my own service checks. But this is not the case.